Advanced Analytical Techniques for Semiconductor Assembly Materials and Processes. Jason Chou and Sze Pei Lim Indium Corporation

Transcription

1 Advanced Analytical Techniques for Semiconductor Assembly Materials and Processes Jason Chou and Sze Pei Lim Indium Corporation

2 Agenda Company introduction Semiconductor assembly roadmap challenges Fine pitch, low stand-off Warpage Smaller Cu-pillar solder cap, fewer flux amount More pre-process and thermal oxidation on bond pad surface Five case studies in using surface analysis tools to drive understanding of semiconductor assembly materials

3 Company Introduction Indium Corporation is a premier materials supplier to global industries including: Electronics assembly Semiconductor Solar energy Thin-film Thermal management

4 Indium Corporation Global Manufacturing and Sales Offices

5 From Mobile to Wearable to IoT Technology driving force: lighter, thinner, smaller

6 Solder Joint Evolution Solder Joint by Package Type Flip-Chip Solder Joint High-Pb Solder Eutectic Solder (PbSn63) SnAg2 Sn(?)

7 Assembly and Process Challenges for FC-BGA Thinner substrates and thinned die increase warpage Processes oxidize / contaminate the ball-attach pad surface Bottom Cu/OSP pads badly oxidized

8 Process and Material Challenges in Flip-Chip Solder Microbump Thickness & alloy Oxidation Contamination IMC thickness No-clean Flux Residue level (ULR) Wetting power Compatibility with MUF/CUF Rheology Substrate or Leadframe Leadframe / Substrate Surface treatment Oxidation Contamination Warpage

9 Advanced Analytical Techniques for Semiconductor Assembly Advanced analytical and preparation techniques now necessary to understand failure modes Auger spectroscopy SIMS (secondary ion mass spectrometry) FIB (focused ion beam) Drive deep understanding of mechanisms

10 Surface Analysis by SIMS / Auger Auger Electron: 0.4 ~ 5nm Secondary Electron (SIMS): <50 nm SEM EDX: 1000 ~ 3000 nm SIMS Auger SEM EDX

11 Case Study 1: Solder Cap Contamination SEM and EDX analysis The SEM did not find foreign or abnormal material EDX analysis showed high C and O levels Good solder joint Bad solder joint

12 Case Study 1: Solder Cap Contamination Solder cap shows abnormal one has dark surface with impurity SIMS data shows abnormal one has high C, O content Abnormal Normal

13 Case Study 2: Wafer Bumping Cleaning Optimization Auger test method is very sensitive to carbon, oxygen (oxide) Good tool for process optimization STD STD (exclude S, Ca) 40S50DI 40S25DI 60S50DI 60S25DI 70S50DI 70S25DI Name Start KE Peak KE End KE PP At. % PP At. % PP At. % PP At. % PP At. % PP At. % PP At. % PP At. % C KL Sn MN O KL S LM Ca LM Ag MN % Carbon Condition

14 Case Study 3: Leadframe Surface Treatment Surface roughness (adhesion enhancement) treatment is used to increase MUF/CUF adhesion Different surface treatment will induce different wetting performance Scanned Area 3.0µ m

15 µ m Scanned Area Case Study 3: Leadframe Surfaces with SIMS Analysis SIMS analysis quantifies oxidation level and oxide depth Important for process tuning 3.50E E E E E E E+08 C 2.00E+08 C 1.50E E+08 O Cu 1.50E E+08 O Cu 5.00E E E E E E E E+08 C O Cu 5.00E+07

16 BGA Process and Thermal Treatment 2~4 times Substrate SMT Reflow Die Bond Wire bond D/B Cure Saw Singulation BM Pre-clean PMC Molding Pre-Baking Many thermal process before BM will induce pad surface oxidation, which will induce yield loss (missing ball ) and low productivity

17 Case Study 4: BM Pad Surface with SIMS Analysis 2~4 times Substrate SMT Reflow Die Bond Wire bond D/B Cure Saw Singulation BM Pre-clean PMC Molding Pre-Baking 1.40E E+08 Fresh substrate 3.50E E+06 Post Molding cure 1.00E E E E E+07 Cu 12C 16O 32S 58Ni 138Ba 197Au 2.50E E E E E+05 O, C 12C 16O 32S 58Ni 138Ba 9.00E E E E E E E E E+07 Flux clean x1 12C 16O 32S 58Ni 138Ba 197Au 9.00E E E E E E E E E+07 Flux clean x2 12C 16O 32S 58Ni 138Ba 197Au

18 Supplier-B Supplier-A Case Study 5: FIB Analysis on OSP Substrate Deposit Pt for FIB analysis OSP Cu Fresh Cu OSP Substrate

19 Case Study 5: FIB and SIMS post-flux clean Indium WS-575-C shows better cleaning efficiency on OSP substrate base on FIB and SIMS analysis result WS-575-C 4.00E E F 4.00E E F 3.00E E E E E+07 12C 16O 32S 58Ni 2.50E E E+07 12C 16O 32S 58Ni 1.00E+07 63Cu 1.00E+07 63Cu 5.00E E E E+07 K-5-NC 5.00E E+07 K-5-F 4.00E E E+07 12C 3.50E+07 12C 3.00E+07 16O 3.00E+07 16O 2.50E+07 32S 2.50E+07 32S 2.00E+07 58Ni 2.00E+07 58Ni 1.50E+07 63Cu 1.50E+07 63Cu 1.00E Au 1.00E Au 5.00E E+06 Competitor OSP residue

20 Summary Advanced analytical techniques create: Knowledge of the mechanisms of flux activity and usage Improved materials and processes Higher yield, improved reliability, and speed time to market

21 Thank you!